Get Grid Column Index, Width and Visibility

Environment

Product

Grid for Blazor, TreeList for Blazor

Description

Solution

This scenario requires knowledge about the Grid State. Get familiar with the following sections first:

• Information in the Grid State
• Grid OnStateChanged Event
• Grid State Methods

There are two ways to obtain the Grid column information programmatically:

• Use the Grid OnStateChanged event and check args.GridState.ColumnStates, where args is the OnStateChanged event argument.
• Use the Grid GetState method and check the ColumnStates property of the returned GridState object.

ColumnStates is a ICollection<GridColumnState>. The GridColumnState class has the following properties:

Property	Type	Description
Index	int	The current index of the column. It will change as a result of column reordering.
Id	string	The Id parameter value of the <GridColumn>.
Field	string	The Field value of the column.
Visible	bool?	Whether the column is visible or hidden.
Locked	bool	Whether the column is locked or not.
Width	string	The width of the column if it is set. It will change as a result of column resizing.

The column order in the ColumnStates collection matches the <GridColumn> tag order in the Grid declaration.

Example

Get current Grid column state

<h1>Get Grid Column Information from State</h1>

<p>Resize, reoder, lock or hide columns...</p>

<TelerikGrid @ref="@GridRef"
             Data="@GridData"
             TItem="@Person"
             ShowColumnMenu="true"
             Reorderable="true"
             Resizable="true"
             OnStateChanged="@GetColumnsFromStateChange">
    <GridColumns>
        <GridColumn Field="@nameof(Person.Id)" Id="person-id" />
        <GridColumn Field="@nameof(Person.FirstName)" Id="person-firstname" />
        <GridColumn Field="@nameof(Person.LastName)" Id="person-lastname" />
        <GridColumn Field="@nameof(Person.Age)" Id="person-age" />
    </GridColumns>
</TelerikGrid>

<h2>Column Information</h2>

<TelerikGrid Data="@ColumnData">
    <GridColumns>
        <GridColumn Field="@nameof(GridColumnState.Id)" />
        <GridColumn Field="@nameof(GridColumnState.Field)" />
        <GridColumn Field="@nameof(GridColumnState.Index)" Title="Index in State" />
        <GridColumn Field="@nameof(GridColumnState.Locked)" />
        <GridColumn Field="@nameof(GridColumnState.Width)">
            <Template>
                @{
                    var dataItem = (GridColumnState)context;
                    if (dataItem.Width != null)
                    {
                        @dataItem.Width
                    }
                    else
                    {
                        <em>null</em>
                    }
                }
            </Template>
        </GridColumn>
        <GridColumn Field="@nameof(GridColumnState.Visible)">
            <Template>
                @{
                    var dataItem = (GridColumnState)context;
                    if (dataItem.Visible.HasValue)
                    {
                        @dataItem.Visible.Value
                    }
                    else
                    {
                        <em>null</em>
                    }
                }
            </Template>
        </GridColumn>
    </GridColumns>
</TelerikGrid>

@code {
    private TelerikGrid<Person> GridRef { get; set; }

    private List<Person> GridData { get; set; } = new List<Person>();
    private List<GridColumnState> ColumnData { get; set; } = new List<GridColumnState>();

    protected override void OnInitialized()
    {
        for (int i = 1; i <= 3; i++)
        {
            GridData.Add(new Person
            {
                Id = i,
                FirstName = $"First Name {i}",
                LastName = $"Last Name {i}",
                Age = i + 20
            });
        }

        base.OnInitialized();
    }

    private void GetColumnsFromStateChange(GridStateEventArgs<Person> args)
    {
        ColumnData = args.GridState.ColumnStates.ToList();
    }

    private void GetColumnsOnDemand()
    {
        ColumnData = GridRef.GetState().ColumnStates.ToList();
    }

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (firstRender)
        {
            GetColumnsOnDemand();

            StateHasChanged();
        }

        await base.OnAfterRenderAsync(firstRender);
    }

    public class Person
    {
        public int Id { get; set; }
        public string FirstName { get; set; } = string.Empty;
        public string LastName { get; set; } = string.Empty;
        public int Age { get; set; }
    }
}

See Also

• Grid State